How do I calculate how long a peptide vial will last?

Divide total vial content by dose size to get total doses, then divide by injection frequency. A 10 mg vial dosed at 2.5 mg once per week lasts 4 weeks. ASCEND's Vial Lasts feature calculates this automatically.

FAQ

How many doses are in a peptide vial?

Q: How many doses are in a peptide vial?

Doses per vial = Total vial content in mg ÷ Dose per injection in mg. For example, a 10 mg tirzepatide vial used at 2.5 mg per dose yields 4 doses. A 5 mg BPC-157 vial at 0.25 mg (250 mcg) per dose yields 20 doses.

Calculating the dose count of a peptide vial lets you plan your supply accurately, estimate cost per dose, and avoid running out mid-protocol. The answer depends on two variables: the total content of the vial in milligrams, and the dose size per injection. This page walks through the formula and common scenarios.

TL;DR - Doses = Vial mg ÷ Dose mg. A 10 mg tirzepatide vial dosed at 2.5 mg/week = 4 doses (4 weeks). A 5 mg BPC-157 vial dosed at 0.25 mg (250 mcg) twice daily = 10 days.

The formula

The core calculation is a single division. Convert all values to the same unit (milligrams) before dividing.

Doses = Vial Content (mg) ÷ Dose Size (mg)

Convert mcg doses to mg by dividing by 1000 first

Example 1: A 10 mg tirzepatide vial, dosing at 2.5 mg per injection. 10 ÷ 2.5 = 4 doses.

Example 2: A 5 mg BPC-157 vial, dosing at 250 mcg (0.25 mg) per injection. 5 ÷ 0.25 = 20 doses.

To calculate how long a vial lasts, divide the total doses by your injection frequency per week. 20 doses at twice daily (14 injections/week) = about 1.4 weeks of supply.

Dose count reference table

Common vial sizes and dose sizes across GLP-1 peptides and research peptides like BPC-157 and TB-500.

Vial Size	Dose/Injection	Total Doses	Weekly (1x/wk)
5 mg	250 mcg (0.25 mg)	20 doses	20 weeks
5 mg	500 mcg (0.5 mg)	10 doses	10 weeks
5 mg	0.25 mg/week	20 doses	20 weeks
10 mg	2.5 mg	4 doses	4 weeks
10 mg	5 mg	2 doses	2 weeks
15 mg	2.5 mg	6 doses	6 weeks
15 mg	5 mg	3 doses	3 weeks

Watch out: Most researchers waste 1–2 doses per vial. This happens when they don't track remaining volume and discard a vial they assume is empty. A vial that feels light may still contain a full dose - always check the remaining volume against your concentration before discarding.

Practical planning notes

Dead volume matters. Most insulin syringes have 0.02–0.05 mL of dead space in the needle hub. At high concentrations, this represents a non-trivial amount of peptide left in the needle after injection. If precision matters, use syringes with integrated (fixed) needles to minimize dead space.

Reconstitution volume also affects your dose count planning. If you add more water than expected (or lose some water volume during needle insertion), your actual concentration will differ slightly from your target. ASCEND's calculator accounts for your exact water volume to give accurate draw-to-unit values.

Tip: The Vial Lasts feature in ASCEND automatically calculates total doses and weeks of supply from your vial size, dose frequency, and reconstitution volume. No spreadsheet needed.

Open Calculator → Browse All FAQ

Research References

USP <797> - Pharmaceutical Compounding: Sterile Preparations
U.S. Pharmacopeia · Vial use, dosing, and beyond-use dating standards

Wang W. - Instability, stabilization of liquid protein pharmaceuticals
Int J Pharm 1999 · PMID 10502313

ASCEND is a mathematical reference tool for research purposes only. Not for medical use.
All FAQ · Calculator